Paint spraying apparatus



Nov. 25, 1941.

T. F. BRACKETT PAINT SPRAYING APPARATUS Filed May 4, 1938 3 Sheets-Sheet1 Snventor I Nov. 25, 1941. T. F. BRACKETT 2263 977 PAINT SPRAYINGAPPARATUS Filed May 4; 1958 s Sheets-Sheet 2 Zhmentor attorneys Nov. 25,1941. T. F. BRACKETT 2,263,977

PAINT SPRAYING APPARATUS Filed May 4, 1958 s Sheets-Sheet 3 Bu i W(Iflomegs Patented Nov. 25, 1941 PAINT SPRAYING APPARATUS Tracy F.Brackett, Detroit, Mich., assignor to General Motors Corporation,Detroit, Mich., a

corporation of Delaware Application May 4, 1938, Serial No. 206,034

2 Claims.

Air brushes are in general use for applying paint coatings and wheremore than one color is needed the practice in paint shops heretofore hasbeen to have several guns, one for each color or type of paint on hand.One of the objects of this invention is to reduce operating costs byenabling the use of the same gun for all colors and accordingly thesystem involves the thorough and quick cleaning of the gun in thechange-over from one color to another.

A further object is to provide for the quick attachment to anddetachment from the gun of the terminal or free end of a selected paintdelivery conduit and for the closure of the. conduit at its free endwhen not in use.

Additional objects and advantages will become apparent during the courseof the following specification having reference to the accompanyingdrawings wherein Figure 1 shows in perspective the system ready for use;Figure 2 is an enlarged view of the detachable valved fitting betweenthe gun and paint supply conduit; Figure 3 is a detail view showing thegun cleaning fixture; Figure 4 is a detail view of the detachablecoupling parts separated one from another; Figure 5 is a sectional viewtaken on line 5-5 of Figure 2; Figure 6 is a detail section taken online 6-6 of Figure 5, and Figures 7 and 8 are sectional views showingmodifications.

Referring to the drawings the automobile body I is shown for the purposeof illustration as the object to be painted. In the manufacture ofautomobiles the assembled bodies are placed on a conveyor line and arepainted as they move along but the schedule may call for difierentcolors on successive bodies. Consequently, several paint containers areneeded as shown at 2-2. Usually the paint within the storage tanks isunder some pressure which helps its movement upwardly through standpipesto which are connected flexible conduits or hoses 3-3. Each hoseterminates at its free end in a valved fitting for attachment to thespray gun shown at 4. This applicator gun is of a conventional type andis provided with an air pressure hose 5 controlled by a suitable triggeractuated valve. When the valve is opened airunder pressure flows throughthe gun and draws paint from the supply hose for discharge through thenozzle 6 as is illustrated by the broken lines in Figure 1.

When a change-over from one color to another is necessary the workmanusing the structure as in Figure 1, places over the nozzle 6 a domedcover 1 preferably provided with a sealing gasket 8, and with the nozzlecovered as shown in Figure 3, opens the air valve whereupon the airunder pressure being trapped by the cover or cap 1 forces any paintwithin the gun back into the paint delivery hose so as to clean the gunpassages and condition it for the next color job. For convenience, thecover I may be mounted on an arm 9 carried by the stand l0, whichsupports the hose ends not in use. If desired the hose may be providedwith a glass window to observe the return of the paint but ordinarilythis will be unnecessary since the workman will soon accustom himself tothe time required to clear the gun. Following the cleaning operation andapproximately coincidental with the release of the valve operatedtrigger the shutoff cock in the hose fitting is moved to closed positionand then the fitting may be disconnected from the gun and laid asidewithout danger of spilling paint or leakage through the free end of thehose. The hose for the desired color is then selected and coupled to thegun and after its valve is opened the spraying operation may be resumed.

The detachable coupling between the gun and hose may involve a nipplecarried by the gun to which is secured the valve fitting on the end ofthe hose. The structure will be best understood from an inspection ofFigure 5 where the numeral ll indicates an apertured boss on the gun towhich is secured by coupling nut [2 the headed end of a tube l3.Threaded or otherwise secured on the tube is a sleeve I4 having anenlarged hollow head I5 at one end to receive a replaceable fiber seatIt. At its opposite end the sleeve M has a squared head I! to which isfitted a squared center opening of a ring I8 having diametricallyopposite pins [9 so that the ring is slidably keyed to the sleeve. Acoil spring 20 interposed between the head I5 and ring l8 urges the rinaway from the head.

The pins l9 form a part of a bayonet slot connection and are receivablewithin slots 2| of the coupling sleeve 22 which is adapted to receivethe nipple on the gun. This sleeve 22 is threaded or otherwise fixedlysecured to an apertured boss or projection 23 extending laterally fromthe valve casing 24 and terminating in a conical nose which seats on thefiber washer 56, the parts being maintained in tight sealing engagementthrough the action of the coil spring 20.. Rotatable within the valvehousing 24 is a tapered valve plug 25 having a transverse bore 26 whichmay be brought into and out of alignment with the aperture in the boss23 and thus constitute a stopcock. Threaded into an enlarged portion ofthe bore 26 is a coupling 21 to which is secured the seating force ofthe spring 53. Prior by the nut 28 the hose fitting 29 which ordinarilyis fitted to the boss H of the gun. Thus the hose is rigidly connectedwith the rotary plug 25 and with the coupler 21 movable within acircumferential slot 39 in the valve casing 24, the hose and associatedcoupler parts act as an operating lever for imparting movement to thevalve plug 25. This operation of the valve is found of considerable helpto the operator, who holds the handle of the gun in one hand and withthe other hand swings the hose with ample leverage to operate the valveeasily. At the same time he may use his thumb to engage the tail 3| of akeeper plate 32 which is keyed to the squared pin 33 projecting from thevalve plug 25 and is provided with an inwardly pressed tooth or detent34 adapted to seat in either of two notches as at 35 spaced apartsubstantially 90 in the end of the valve casing 24 and which notchesdetermine the open and shut positions of the valve. To maintain theparts against accidental slippage from adjusted position a coil spring36 bears against the plate 32 at one end and at its opposite end againsta washer 31 held on the projection 33 by a cotter pin 38. This springincidentally holds the conical plug 25 within the tapered casing 24.

As seen particularly in Figure 4 the coupling sleeve 22 is provided withcut out portions as at 39 which expose the tapered end of the projection23 and render this part easily accessible for cleaning.

In the structure of Figure '7 an auxiliary selfclosing valve is providedat the tip end of the hose fitting to retain the paint when the hose isuncoupled and to eliminate the need for the nozzle cover I previouslyreferred to. This valve extends as close as feasible to the paintdischarge nozzle of the gun and, consequently, only a small amount ofpaint is contained in the nozzle beyond the valve. When changing overfrom one color to another it is only this small amount of paint which islost and this is removed with one or two shOIt shots preliminary todirecting the gun toward the work for the application of a differentcolor. In this view also is illustrated the use of an ordinary pet cock,whose body 49 contains the rotary plug 41 having a handle 42. One end ofthe valve body 48 is threaded as at 43 for connection with the usualhose and the other end 44 is threaded for connection with the couplingsleeve 45. The sleeve 45 through a pair of bayonet slots detachablyreceives the pins 45 on the non-rotatable collar slidably fitted to thehollow tube assembly 4'! carried by the gun. In this instance the hollowcoupler assembly of the gun encloses a long tubular extension or pipe 48fitted at one end in the threaded end 44 of the detachable hose fitting.At its opposite end the tube 48 is formed with an internal rib 49 havinga tapered seat for the conical valve 50. A wire secured by a drop ofsolder '52 to the valve 59 extends through the tube and terminates in aspring coil 53 bearing against the inner end of the tube and exertingits force to seat the valve.

When the paint supply hose is coupled to the gun and the handle 42turned to open the main valve the spraying operation will be undercontrol of the operator in the usual manner. The movement of paint tothe gun nozzle will unseat the self-closing valve 59. The unseating isfacilitated by reason of the restricted diameter of the internal rib 49which serves to increase t ressure acting on the valve to overcome Pam pto (11$- connection of the paint supply hose the main valve 4! is closedand with the hose uncoupled the paint in the long tube 48 is retained bythe valve as long as the hose is not in use. The paint in the gun beyondthe valve 50 will be of a small amount and may be quickly discharged bya short flow of air through the gun. Ordinarily this could be done afterthe gun is coupled to a different hose and since it is customary to testpaint flow before starting the spraying operation on the work thistesting operation will clear the gun of the previous color without anymore waste than would otherwise occur.

The structure of Figure 8 differs primarily in the provision of a mainvalve for the free end of the hose which is opened and closedautomatically with the coupling and uncoupling operations, respectively.In this instance the gun fitting includes the fixed coupling member 55carrying pins 56 which engage bayonet slots in the detachable hosecoupling socket or sleeve 51. The end of the gun carried member, 55 isprovided with a sealing washer 58 having a tapered seat to receive thetapered nose of the collar 59 slidably guided in the internal rib 60 ofthe coupling sleeve 51. This collar forms a part of a movable valveassembly including a hollow stem BI and a head 62 as well as the tubularextension 63 adapted to project into the gun to a point near thedischarge nozzle and provided at its tip with a self-seating check valve64 on the end of the wire 65 terminating in the spring coil 66. Thevalve head 52 acts against a coil spring 61 seating on the hosefastening nipple 68, whose skirt threads into the socket 51 and holds inplace a valve seat 69 of hard fiber or the like as well as a ring 10. Tothering I0 is secured one end of an expansi'ble bellows 'll having itsopposite end attached to the collar 59 and serving as a seal againstpaint leakage. In the coupled position of the parts illustrated the mainvalve 62 is moved from its seat 69 through engagement of the collar 59and abutment 58 and paint from the hose is free to enter the hollow stemthrough one or more side openings 12. When the gun trigger is actuatedthe movement of the paint will open the auxiliary valve 64 as beforedescribed. Similarly only a small amount of paint remains in the gunwhen a change-over from one hose to another is made and this is clearedout upon initial operation of the trigger. As soon as the parts areuncoupled the main valve 62 is closed automatically by the action of thespring 61.

From the above description it will be apparent that there has beenprovided an arrangement to enable transfer of the gun from one colorsupply line to another in the interval required for the conveyor to takeup the spacing between successive. bodies and bring up the next body tothe workmans station.

I claim:

1. In combination, a pair of detachable coupling-members, a tubularelement slidably mounted in one of the members and projected therefromfor insertion in the other member, a valve formation on said element toclose communication between the interior of the element and itsassociated coupling member, spring means urging the element outwardly toseat said valve, an abutment on said other member engageable with theelement in the coupled relation of the parts to shift the element andunseat said valve,

and an outwardly opening spring pressed check valve carried by theprojected element to seat on the tip thereof.

2. For connection with a tubular coupling member, a coupling head havingan internal valve seat, a spring seated valve engaging said seat andhaving a hollow guide stem slidably mounted within said head andprojected therebeyond for telescopically fitting within the couplingmember, a check valve carried by and closl0

